Compounds having hydrogenated ring systems and process of preparing them



I -Patented Jan. 23, 1934 UNITED STATES COMPOUNDS HAVING HYDROGENATED RING SYSTEMS AND PROCESS OF PRE- PARHVG THEM Otto Diels and Kurt Alder, Kiel, Germany, assignors to I. G. Farbenindustrie Aktiengesellschaft, Frankfort-on-the-Main, Germany No Drawing.

Original application October 29,

1928, Serial No. 315,915, and in Germany November 5, 1927. Divided and thisapplication January 13, 1930. Serial No. 420,626

16 Claims.

The present invention relates to compounds having hydrogenated ring systems and to processes of preparing them.

This invention is based on the discovery that compounds with a system of conjugated-C Cdouble bonds, as for instance butadiene, cyclopentadiene, phellandrene, myrcene or the like easily form condensation products with acrylic acid, acrolein and other unsaturated compounds of the following general formula:

R1 R1 H=$H wherein R1 stands for a I? 0 CH,COH oralkyl group and R2 for hydrogen or alkyl in such a manner that the last named compounds are firmly linked to the systems with conjugated carboncarbon double bonds, the double bond in 1:4 position being opened up.

Also pyrrol and substituted pyrrols, furthermore furanes and other similar compounds are likewise susceptible of reacting with the aforesaid compounds.

Thus acrolein, acrylic acid and ethylidene acetone react for instance easily with cyclopentadiene with formation of the corresponding monobasic hydrogenated acid and aldehyde and ketone respectively:

vention is, therefore, of a very great value for' industrial purposes.

The following examples illustrate the inven- 0 tion:

(1) End0meth1/Zene-3:6 tetrahydro A benzaldehyde A solution of 10 parts by weight of acrolein in 15 parts by weight of other is mixed with 14 parts by weight of cyclopentadiene. The reaction sets in with evolution of heat. When the conversion is complete the product is fractionated in a raw- (4) Reaction of crotonic aldehyde with u-phe l- (2) Endomthylene 3:6 tetrahz dro A benzoic acid '70 Molecular proportions of acrylic acid and cyclopentadiene are mixed together. Heat is evolved and when the reaction is complete, the

product is distilled under diminished pressure. Thus endomethylene 3:6 tetrahydrobenzoic acid is obtained as an oil of intense Valerian odor. The boiling point is 128 C.-130 C. under a pressure of about 15 mm.

(3) Reaction of crotonic aldehyde with myrcene 10 parts by weight of myrcene and 10 parts by weight of crotonic aldehyde are heated in a pressure vessel to 150 C. The reaction mixture is subjected to the distillation in a vacuum, whereby the aldehyde is obtained as a transparent oil at 143 C. to 144 C. under 12 mm. pressure. By. a repeated distillationit is obtained in an entirely pure state. It probably has the following constitution:

landrene 10 parts by weight of a-phellandrene and 10 parts by weight of crotonic aldehyde are caused to react with one another under the above indicated conditions. The reaction mass. is worked up in an analogous manner and the new aldehyde is obtained at 143 C. to 144 C. under 18 mm. pressure. Its smell and appearance are the same as those of the other aldehydes above described. It probably has the following constitutiom- BIC- 0 omn 11-03 (6) Reaction of crotonic aldehyde the new body.

(5) Reaction of acrolein with u-phellandrene 10 parts by weight of acrolein are caused to react with 22 parts by weight of a-phellandrene in the aforesaid manner. When distilling the reaction mixture in a vacuum, the almost pure aldehyde distils over at 128 C.130 C., under. a pressure of 12 mm. and is obtained in an entirely pure state by repeating the distillation."

The aldehyde is like the above described alde-. hydes an oil clear as water and .is distinguished by the same characteristic odor. It probably has the following constitution:

011-011 CH-C=O H-CH H: CHa

crotonic aldehyde with dimethylbutadiene 5 parts by weight of 2.4-dimethylbutadiene (obtained from dimethylbutan-diol of the following formula:

(7) Reaction of CH3 cHr-o-oHFom-cm by separation of 2 molecular proportions of water) and 10 parts by weight of crotonic aldehyde are treated in the above described man= ner. By distillation in a vacuum the reaction product is obtained in an almost pure and by a second distillation in a perfectly pure state. It boils at 81 C. to 82 C. under. 12 mm. pres= sure and probably has the following constitution:

cm-c-om-on-cm o H-cn n-g-n It has the same characteristic smell as the above indicated aldehydes.

(8) Reaction by crotonic aldehyde with isoprene and 12 parts by 8 parts by weight of isoprene treated as indiweight of crotonic aldehyde are cated in the preceding example. The reaction mixture is distilled in a vacuum. A quantity of crotonic aldehyde first distils over, and afterwards almost pure dimethyl 3:6-A -tetrahydrobenza1dehyde which is obtained in an entirely pure state by a second distillation; It boils at 92 It boils at 63 0.44? C. under 10 mm. pressure.

under 25 mm. pressure and probably has the fol lowing constitution: 1

' on-cm-on-cm The smell is similar to that of the aldehyde described in the preceding example, but not so penetrating. I

- (9) Reaction of crotonic aldehyde with pp'-dimethylbutadiene 8 parts by weight of pW-dimethylbutadiene and 13 parts by weight of crotonic aldehyde are heated in apressure vessel to about 150 C. for 5 hours. The reaction product is distilled in a vacuum. Crotonic aldehyde first distils over and then the new trimethyl 3.4.6-A -tetrahydrobenzaldehyde in an almostpure state. After another distillation in a vacuum it shows the constant boiling point of 89 C. under 12 mm pressure. It probably has the following constitution:

om-o-cm-on-Cra om-c-cm-ort-rQ-n It has a characteristic, slightly penetrating smell.

(10) Reaction of acrolein with 2.3-dim ethylbutadiene By heating molecular quantities of; 2.3-dimethylbutadiene and a'crolein in a pressure vessel to 100 C. for about 3 hours and then fractionating the contents of the vessel in a vacuum, the no I dimethy1-3.4-A -tetrahydrobenzaldehyde is obtained in a good yield as a colorless oil of an intense odor of leaves and boiling at 79 C. under 10 mm. pressure. It has probably the following constitution: 1

CHr-C-CHr-CH:

o a 0H3- -0 H- -H (11) Reaction of acrolein with isoprene Acrolein is easily condensed with isoprene in a pressure vessel by heating the components to- 100 C. as it has been described in the preceding examplegiven for dimethyl-2.3-butadiene..

The methyl 3.-(4?) -A -tetrahydrobenzaldehyde thus obtained in a .good yield is very similar to its homologues as regards its smell, behavior and appearance. It has probably the following constitution:

, OH-CHr-CH: O CHa-GC.Hr- LEI- a (12) Reaction of acrolein with myrcene 'Myrcene is easily-condensed with acrolein by heating the two components in a pressure vessel to 100 C. v

The isohexenyl-3- (4? -A tetrahydrobenzaldehyde thus obtained is a colorless oil of a very agreeable intensity fruit-like odor. It boils at C. to 142 C. under 10 mm. pressure. It probably has the following constitution:

(13) Reaction of acrolein with 2.4-dimethulbutadiene This reaction is easily effected by heating molecular quantities of 2.4-dimethylbutadiene and acrolein in a pressure vessel to 100 C. for about three hours. The aldehyde thus obtained is very similar to that of its above described isomerlde. It is a colorless liquid of an intensely grass-like odor boiling at 86 C. to 88 C. under 12 mm. pressure and probably has the following constitution:

onro--cn, cn, o

OHCH H] I a H (14) Reaction of cyclopentadiene with crotom'c aldehyde 8 parts by weight of crotonic aldehyde are heated in a pressure vessel with 10 parts by'weight of freshly distilled cyclopentadiene to about 100 C. for 4 hours. The reaction mixture is then distilled in a vacuum, whereby under 12 mm. pressure a'colorless oil is obtained distilling over at 60 C. to 85 C. and representing a mixture of two stereo isomeric aldehydes. They probably have the following constitution:

- CH-CH- (15) 84 parts by weight of ethylidene-acetone 0f the formula CH3CH=CH-CO -CH3 and 99 parts by weight of freshly distilled cyclopentadiene are heated in a pressure vessel to 150 C.

for 5 hours. The feebly greenish-yellow liquid is distilled in a vacuum. The main fraction boils at 76 C.- C. under 13 mm. pressure. It is a transparent mobile oil of a camphor-like odor.

This application is a division of our application Ser. No. 315,915 filed October 29, 1928.

We claim:

1. The process of preparing compounds having a hydrogenated ring system which comprises causing a compound of the following formula:

R1 2 nc=cn wherein R1 stands for a and R2 for hydrogen or alkyl to react with a compound containing a system of two conjugated carbon-carbon double bonds.

2. The process of preparing compounds having a hydrogenated ring system which comprises causing a compound of the following formula:

' Bi R,

wherein R1 stands for a and R: for hydrogen or alkyl to react with a compound of the following formula:

x i i i wherein x stands for hydrogen or two of the Xs stand for alkyl.

3. The process of preparing compounds having a hydrogenated ring system which comprises causing a compound of the following formula:

1 R: Hc=cH wherein R1 stands for a o 0 0 -&, or &alkyl group and R2 for hydrogen or alkyl to react with a com pound of the following formula:

' H2C=CC=CHXa wherein X1, X2 and X2 stand for hydrogen'or two of the X's stand for alkyl.

4. The process of preparing compounds having a hydrogenated ring system which comprises causing a compound of the following formula:

wherein Ra stands for hydrogen or methyl to react with a compound of the following formula:

wherein X1, X2 and X3 stand for hydrogen or two of the X's stand for alkyl.

5. Theprocess of preparing compounds having ing a. hydrogenated ring system which comprises causing crotonic aldehyde to react with 2.4-

dimethylbutadiene.

v8. Compounds. of the following probable formula:

l H-C-Ri wherein each of R1, R2, R3 and R4 is hydrogen or alkyl, R5 is hydrogen and Re is hydrogen or alkyl or R5 and R0 together form an alkylene chain contained within a ring of six carbon atoms, as indicated above, and in every instance at least pound containin 4- one of R2, R3, R4 and R6 is hydrogen, saidcompounds being obtainable by causing a compound of the formula:

R1 R1 hat];

wherein R1 stands for a 0' 0 H g -C,or -alkyl group and R: for hydrogen or alkyl to react with a coma system of two conjugated carbon-carbon double bonds.

9. Compounds of the following formula:

wherein Z stands for hydrogen or alkyl and at least one Z must be hydrogen.

10. Compounds of the following formula:

z o ll z-c- HCH(.|l 11 z- -cH1cn-z wherein Z stands for hydrogen, methyl and at least one Z must be hydrogen.

' 11. Compounds of the following formula:

wherein Z: stands for hydrogen or methyl and Z: for hydrogen or methyl and at least one Z must be hydrogen.

. 12. Compounds of the following formula:

u Htfi-(IH-CH-C-H z -c-cnr-cn-om wherein Z1 stands for hydrogen or methyl.

13. The compound probably of the following formula:

' CH: O

(l: I H(fi HCHC-H cm-c-cm-cH-cm forming an oil and boiling at between 81 C. and

82 C. under a pressure of 12 mm.

14. The compounds of the following formula:

v o CHr-C-CHr-UH-Hl-H cm-Y -cH,- H-OH: said product boiling at 89 C. under 12 mm. pressure and having a characteristic, slightlypenetrating smell.

O'I'IO DIELS. KURT ALDER. 

